In recent years, continuous advancement of display technologies results in increasing demands on display quality of displays, such as image resolution, color saturation, and so on. In addition to the requirement for high image resolution and high color saturation, a touch control interface that allows a user to directly touch a display image and thereby interact with the display image has also been developed, such that the user's need of interacting with the display image may be satisfied.
At present, most touch control interfaces are operated by human's fingers touching touch panels to receive corresponding messages or feedbacks. However, due to frequent and constant touch actions, the touch interfaces may harbor germs or bacteria. Besides, under certain circumstances, e.g., given that the user's fingers have dirt or smudges, the user may not be comfortable with using the touch control interfaces and interacting with the display image for fear of smearing the touch panels.
To prevent the touch control interfaces from being stained or polluted, manufacturers have been looking forward to the development of an air-touch interface for a user to interact with floating images in virtual space. Accordingly, how to exclude display images from the limitation of varied distance between a user and the display apparatus is one of the significant issues to be resolved by the industry.